QSsl Namespace

The QSsl namespace declares enums common to all SSL classes in Qt Network. More...

Header: #include <QSsl>
CMake: find_package(Qt6 COMPONENTS Network REQUIRED)
target_link_libraries(mytarget PRIVATE Qt6::Network)
qmake: QT += network


enum class AlertLevel { Warning, Fatal, Unknown }
enum class AlertType { CloseNotify, UnexpectedMessage, BadRecordMac, RecordOverflow, DecompressionFailure, …, UnknownAlertMessage }
enum AlternativeNameEntryType { EmailEntry, DnsEntry, IpAddressEntry }
enum EncodingFormat { Pem, Der }
enum class ImplementedClass { Key, Certificate, Socket, DiffieHellman, EllipticCurve, …, DtlsCookie }
enum KeyAlgorithm { Rsa, Dsa, Ec, Dh, Opaque }
enum KeyType { PrivateKey, PublicKey }
enum SslOption { SslOptionDisableEmptyFragments, SslOptionDisableSessionTickets, SslOptionDisableCompression, SslOptionDisableServerNameIndication, SslOptionDisableLegacyRenegotiation, …, SslOptionDisableServerCipherPreference }
flags SslOptions
enum SslProtocol { TlsV1_0, TlsV1_0OrLater, TlsV1_1, TlsV1_1OrLater, TlsV1_2, …, SecureProtocols }
enum class SupportedFeature { CertificateVerification, ClientSideAlpn, ServerSideAlpn, Ocsp, Psk, …, Alerts }

Detailed Description

Type Documentation

[since 6.0] enum class AlertLevel

Describes the level of an alert message

This enum describes the level of an alert message that was sent or received.

QSslSocket::AlertLevel::Warning0Non-fatal alert message
QSslSocket::AlertLevel::Fatal1Fatal alert message, the underlying backend will handle such an alert properly and close the connection.
QSslSocket::AlertLevel::Unknown2An alert of unknown level of severity.

This enum was introduced or modified in Qt 6.0.

[since 6.0] enum class AlertType

Enumerates possible codes that an alert message can have

See RFC 8446, section 6 for the possible values and their meaning.


This enum was introduced or modified in Qt 6.0.

enum QSsl::AlternativeNameEntryType

Describes the key types for alternative name entries in QSslCertificate.

QSsl::EmailEntry0An email entry; the entry contains an email address that the certificate is valid for.
QSsl::DnsEntry1A DNS host name entry; the entry contains a host name entry that the certificate is valid for. The entry may contain wildcards.
QSsl::IpAddressEntry2An IP address entry; the entry contains an IP address entry that the certificate is valid for, introduced in Qt 5.13.

See also QSslCertificate::subjectAlternativeNames().

enum QSsl::EncodingFormat

Describes supported encoding formats for certificates and keys.

QSsl::Pem0The PEM format.
QSsl::Der1The DER format.

[since 6.1] enum class ImplementedClass

Enumerates classes that a TLS backend implements

In QtNetwork, some classes have backend-specific implementation and thus can be left unimplemented. Enumerators in this enum indicate, which class has a working implementation in the backend.

QSslSocket::ImplementedClass::Key0Class QSslKey.
QSslSocket::ImplementedClass::Certificate1Class QSslCertificate.
QSslSocket::ImplementedClass::Socket2Class QSslSocket.
QSslSocket::ImplementedClass::DiffieHellman3Class QSslDiffieHellmanParameters.
QSslSocket::ImplementedClass::EllipticCurve4Class QSslEllipticCurve.
QSslSocket::ImplementedClass::Dtls5Class QDtls.
QSslSocket::ImplementedClass::DtlsCookie6Class QDtlsClientVerifier.

This enum was introduced or modified in Qt 6.1.

enum QSsl::KeyAlgorithm

Describes the different key algorithms supported by QSslKey.

QSsl::Rsa1The RSA algorithm.
QSsl::Dsa2The DSA algorithm.
QSsl::Ec3The Elliptic Curve algorithm.
QSsl::Dh4The Diffie-Hellman algorithm.
QSsl::Opaque0A key that should be treated as a 'black box' by QSslKey.

The opaque key facility allows applications to add support for facilities such as PKCS#11 that Qt does not currently offer natively.

enum QSsl::KeyType

Describes the two types of keys QSslKey supports.

QSsl::PrivateKey0A private key.
QSsl::PublicKey1A public key.

enum QSsl::SslOption
flags QSsl::SslOptions

Describes the options that can be used to control the details of SSL behaviour. These options are generally used to turn features off to work around buggy servers.

QSsl::SslOptionDisableEmptyFragments0x01Disables the insertion of empty fragments into the data when using block ciphers. When enabled, this prevents some attacks (such as the BEAST attack), however it is incompatible with some servers.
QSsl::SslOptionDisableSessionTickets0x02Disables the SSL session ticket extension. This can cause slower connection setup, however some servers are not compatible with the extension.
QSsl::SslOptionDisableCompression0x04Disables the SSL compression extension. When enabled, this allows the data being passed over SSL to be compressed, however some servers are not compatible with this extension.
QSsl::SslOptionDisableServerNameIndication0x08Disables the SSL server name indication extension. When enabled, this tells the server the virtual host being accessed allowing it to respond with the correct certificate.
QSsl::SslOptionDisableLegacyRenegotiation0x10Disables the older insecure mechanism for renegotiating the connection parameters. When enabled, this option can allow connections for legacy servers, but it introduces the possibility that an attacker could inject plaintext into the SSL session.
QSsl::SslOptionDisableSessionSharing0x20Disables SSL session sharing via the session ID handshake attribute.
QSsl::SslOptionDisableSessionPersistence0x40Disables storing the SSL session in ASN.1 format as returned by QSslConfiguration::sessionTicket(). Enabling this feature adds memory overhead of approximately 1K per used session ticket.
QSsl::SslOptionDisableServerCipherPreference0x80Disables selecting the cipher chosen based on the servers preferences rather than the order ciphers were sent by the client. This option is only relevant to server sockets, and is only honored by the OpenSSL backend.

By default, SslOptionDisableEmptyFragments is turned on since this causes problems with a large number of servers. SslOptionDisableLegacyRenegotiation is also turned on, since it introduces a security risk. SslOptionDisableCompression is turned on to prevent the attack publicised by CRIME. SslOptionDisableSessionPersistence is turned on to optimize memory usage. The other options are turned off.

Note: Availability of above options depends on the version of the SSL backend in use.

The SslOptions type is a typedef for QFlags<SslOption>. It stores an OR combination of SslOption values.

enum QSsl::SslProtocol

Describes the protocol of the cipher.

QSsl::TlsV1_0OrLater5TLSv1.0 and later versions.
QSsl::TlsV1_1OrLater6TLSv1.1 and later versions.
QSsl::TlsV1_2OrLater7TLSv1.2 and later versions.
QSsl::DtlsV1_0OrLater9DTLSv1.0 and later versions.
QSsl::DtlsV1_2OrLater11DTLSv1.2 and later versions.
QSsl::TlsV1_312TLSv1.3. (Since Qt 5.12)
QSsl::TlsV1_3OrLater13TLSv1.3 and later versions. (Since Qt 5.12)
QSsl::UnknownProtocol-1The cipher's protocol cannot be determined.
QSsl::AnyProtocol3Any supported protocol. This value is used by QSslSocket only.
QSsl::SecureProtocols4The default option, using protocols known to be secure.

[since 6.1] enum class SupportedFeature

Enumerates possible features that a TLS backend supports

In QtNetwork TLS-related classes have public API, that may be left unimplemented by some backend, for example, our SecureTransport backend does not support server-side ALPN. Enumerators from SupportedFeature enum indicate that a particular feature is supported.

QSslSocket::SupportedFeature::CertificateVerification0Indicates that QSslCertificate::verify() is implemented by the backend.
QSslSocket::SupportedFeature::ClientSideAlpn1Client-side ALPN (Application Layer Protocol Negotiation).
QSslSocket::SupportedFeature::ServerSideAlpn2Server-side ALPN.
QSslSocket::SupportedFeature::Ocsp3OCSP stapling (Online Certificate Status Protocol).
QSslSocket::SupportedFeature::Psk4Pre-shared keys.
QSslSocket::SupportedFeature::SessionTicket5Session tickets.
QSslSocket::SupportedFeature::Alerts6Information about alert messages sent and received.

This enum was introduced or modified in Qt 6.1.

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